Phenomenological comparison between the flexural performance of steel- and CFRP-reinforced concrete elements

In recent decades, FRP reinforcement has received increasing attention in engineering research of reinforced concrete composites due to its advantages over steel reinforcement, such as corrosion resistance and high strength. Due to brittle failure and high strength-to-stiffness ratio of the FRP reinforcement, the flexural behavior of FRP-reinforced beams exhibits a qualitative and quantitative difference compared to conventional steel-reinforced elements. In particular, understanding and improving material utilization is crucial to reduce material consumption and maximize design efficiency in view of the increasing environmental concerns. In this paper, a phenomenological comparison of the flexural behavior and material utilization for various design configurations for steel-and CFRP-reinforced elements is presented. The investigations include different concrete grades, FRP reinforcement properties, cross-section shapes, and hybrid steel-FRP reinforcement cross -sections. In order to deliver a comprehensive perspective to design efficiency in practical context, serviceability deflection limit has been derived for FRP reinforced elements and integrated into the evaluation scheme. Additionally, a general modeling framework for the investigation of the moment-curvature and load-deflection response of steel-and FRP-reinforced beams has been developed supporting the presented studies. The modeling approach is based on a numerical evaluation of the cross-section equilibrium and it supports different material laws as well as arbitrary cross-section shapes and reinforcement layouts. The obtained results show fundamental differences between the bending capacity and material utilization of steel-and FRP-reinforced elements, which can stimulate the development of resource efficient designs. A deeper understanding of the phenomenology based on the present studies can streamline the current research on innovative design concepts for FRP-reinforced concrete elements with optimal utilization of these high-performance materials.